The Doberman is one of the few dog breeds named after the man who made it, and he made it to protect himself at work.
Karl Friedrich Louis Dobermann was born in 1834 and died in 1894. He lived in Apolda, in the Grand Duchy of Saxe-Weimar-Eisenach in Germany. Wikipedia says he worked as a local tax collector and ran the town's dog pound. The American Kennel Club adds night watchman, dog catcher and dog skinner to the list.
His tax rounds took him through areas that Wikipedia describes as dangerous and bandit-infested. He wanted a dog with strength, loyalty, intelligence and ferocity. The pound gave him a ready supply of dogs to choose from, and he began breeding around 1890.
Nobody wrote down the recipe. Wikipedia says the exact mix is uncertain, though many experts point to the Beauceron, German Pinscher, Rottweiler and Weimaraner. The AKC suggests the old German Shepherd Dog, the Rottweiler, the German Pinscher and the Weimaraner. Later crosses with the Greyhound and Manchester Terrier, around 1900, are the best documented.
Others finished the job. Otto Göller, a liqueur maker in Apolda, founded the first club about five years after Dobermann's death and helped write the first standard.
The name has changed shape twice since. After his death, Germans called the breed the Dobermann-pinscher. Etymonline traces Pinscher to a German name for a short-coated terrier, probably from English pinch, for the clipped ears. About fifty years later, German breeders dropped "pinscher," which means terrier, as inappropriate. The British followed a few years after. Wikipedia says the United States and Canada are the only countries still using Doberman Pinscher.
Those two countries also dropped an "n" from the surname, which is why Americans write Doberman. Merriam-Webster dates Doberman pinscher in English to 1917.
Sources do not even agree on his first names. Merriam-Webster gives him as Friedrich Ludwig Dobermann, while Wikipedia and the AKC use Karl Friedrich Louis.